1. Field of the Invention
The present invention relates to a plate-shaped heating panel with an inner fluid pathway formed therein, and more particularly to a heating panel, which has connecting members fastened to each other by means of a resin, thereby enhancing pressure resistance.
2. Description of the Related Art
Generally, a heating system, having been applied to residential buildings, such as houses, villas, and apartments, employs a structure involving a wet heating process, in which a pipe is laid under a flooring material of a room in a building and supplied with heating fluid, such as heating water, thereby heating the room of the building. However, such a wet type heating system has a lower heating efficiency, resulting in large thermal losses, and requires lengthy concrete curing, resulting in extended construction time. Furthermore, upon leakage of water from the pipe, a mortar layer of the heating system must be broken for repair, thereby impeding easy overhaul while increasing overhaul costs.
In order to solve the problems of the conventional wet heating system as described above, a dry heating panel, made of concrete, a synthetic resin or yellow clay, was developed. The dry heating panel is embedded with a pipe for carrying heating water therein or provided with grooves or fixing members for inserting the pipe for carrying heating water. The dry heating panel is an assembly heating panel, and has advantageous effects in that the construction of the heating system may be completed by simply assembling previously produced pieces of the dry heating panel, thereby reducing the construction time, and simplifying maintenance and overhaul operations thereof. However, the dry heating panel has problems in that, since it adopts a line heating structure in which radiation heat is mainly concentrated where the pipe for carrying heating water is located, generating a severe temperature variation in the heating system, the dry heating panel is ineffective in view of heating efficiency, and in that, since the pipe itself is made of metal or a synthetic resin, it is expensive, resulting in increased construction costs. Furthermore, thermal loss may occur due to piping, and dewing phenomenon may occur on the surface of the pipe, thereby wetting the panel.
In order to solve the problems of the conventional dry heating panel described above, as disclosed in U.S. Pat. No. 5,080,166 and Korean patent application Laid-open publication No. 2002-95733, a plate-shaped heating panel provided with an inner fluid pathway for allowing the heating water to flow therethrough was developed. Compared with the dry type heating system adopting the line heating structure, the plate-shaped heating panel having the inner fluid pathway therein adopts a plane heating structure in which the heating water flows not in a local area but in an overall area of panels, so that it provides very high heating efficiency, resulting in reduction of fuel expenses, and so that the pipe is not required for the structure of the plate-shaped heating panel, thereby eliminating a complicated piping work and reducing the expenses for piping. Additionally, the plate-shaped heating panel is not subjected to the thermal loss and the dewing phenomenon, which usually occurs on the surface of the pipe in the structure of the dry heating panel, and allows a weight of the panel to be reduced. Furthermore, the plate-shaped heating panel is very easy to construct and repair.
Conventionally, the plate-shaped heating panel with an inner fluid pathway formed therein was formed by way of blow molding, as also known as hollow molding. The blow molding is a molding method which forms a hollow product by blowing air into a separating mold, in which molten thermoplastic forming material is inserted and then softened with heat.
Conventionally, upon manufacturing the plate-shaped heating panel by way of the blow molding, when a thermoplastic resin is compressed by a molding plate after the resin is pushed in an extrusion die, hot air is blown into the resin in a cylindrical shape. At this time, since the resin has a temperature decreased below the melting point of the resin, bonding between the resin parts is incomplete. Accordingly, the inner fluid pathway has a hexagonal shape with upper and lower portions parallel to each other, and is formed at right and left sides thereof with notches (each of which is an edge submerging a small angle between symmetrical lines).
In the case where heating fluid of a high pressure flows through the inner fluid pathway of the heating panel, a stress is concentrated on the notches of the inner fluid pathway, causing an initial crack around the notches. The crack is advance along the boundary of plates where the resin is compressed by the mold, resulting in a phenomenon wherein upper and lower plates are separated from each other.